Filter Device for Fluids

ABSTRACT

A filter device for fluids, in particular for low viscosity fluids such as water, comprising a filter housing ( 1 ) in which element holders ( 31 ) are provided for a plurality of filter elements ( 21 ), whose filter medium ( 35 ) in the filter housing ( 1 ) separates an unfiltered side ( 5 ) from a clean side ( 7 ), wherein the filter housing ( 1 ) can be opened for the purpose of inserting and removing the filter elements ( 21 ), is characterized in that a carrier in the form of a basket ( 19 ) is provided for the filter elements ( 21 ), said basket can be inserted into and removed from the filter housing ( 1 ), and the filter elements ( 21 ) can be releasably secured at said basket.

The invention relates to a filter device for fluids, in particular for low viscosity fluids such as water, comprising a filter housing in which element holders are provided for a plurality of filter elements, whose filter medium in the filter housing separates an unfiltered side from a clean side, wherein the filter housing can be opened for the purpose of inserting and removing the filter elements. Furthermore, the invention relates to a filter cartridge for use in such a filter device as well as to a filter element as a component of such a filter cartridge.

Filter devices of the aforementioned type are state of the art and are used in a variety of fields. A few examples that can be mentioned from the vast number of possible applications include the application for water treatment, potable water filtration, the production of pure water and ultrapure water, the filtration of cooling lubricants and washing fluids, etc. With respect to the state of the art, reference is made to the line filter, which is marketed by the applicant under the product name PLF1 and embodies a filter device of the type described in the foregoing.

When such line filters are to be used for applications in which a fine filtration of large volumetric flow rates is necessary and a correspondingly large filter surface area, for example, exceeding 500 m², has to be provided, problems arise both with respect to the design of the filter housing and with respect to carrying out the replacement procedures for replacing the used filter elements. In the case of filter surface areas exceeding 500 m² and filter elements in the form of conventional filter cartridges having a diameter of 67 mm and a length of 40 inches, dimensions that correspond to a filter surface area of about 1 m², the filter housing must provide more than 500 element holders as installation slots for the filter elements. The result is housing dimensions that are difficult to service, in particular, with respect to replacing the elements. Therefore, the state of the art provides such filter surface areas only by means of a plurality of filter housings.

With respect to this problem, the object of the present invention is to provide a filter device conforming to the genre under consideration that provides a filter surface area which inside a filter housing is considerably larger than that of the conventional filter devices but nevertheless is characterized by its extreme ease of maintenance with respect to the replacement of the used filter elements.

The invention achieves this object by means of a filter device having the features specified in claim 1 in its entirety.

Accordingly, an essential feature of the invention consists in the fact that a carrier in the form of a basket is provided for the filter elements, said basket can be inserted into and removed from the filter housing, and the filter elements can be releasably secured at said basket. Owing to the fact that a basket holding the filter elements is provided as a replaceable insert of the filter housing, a large number of filter elements can be removed jointly from the housing and inserted into said housing. This makes the maintenance work associated with the replacement of the elements much simpler, even if the basket has a large number of filter elements in order to achieve large filter surface areas. Since this significantly increases the weight of the basket, said basket can be lifted out of the housing, for example, by attaching a lifting tool and then moving said basket into a position outside the housing, in which the basket can be easily and conveniently equipped with new elements. The resulting ease of maintenance also permits the filter device to be used even under challenging conditions, such as on drilling platforms in offshore oil fields. If during the operation of the respective oil fields a pressure increase is necessary, treated sea water is pumped from a corresponding drilling platform into the oil field. In such applications the filter device, which is provided for treating the sea water, is designed for a filter surface area exceeding 500 m² at a filter fineness of 5μ. Thanks to the arrangement of the filter elements in a basket, which can be removed from the filter housing, these requirements can be met with a single filter housing. In addition, the replacement of the filter elements can be carried out easily and reliably, after the basket has been removed by means of a lifting means, on board the platform even under harsh environmental conditions.

In advantageous exemplary embodiments, the basket has a support plate, which in the installation position in the housing separates the unfiltered side from the clean side and has fluid flow passages for forming the element holders. In this context, the filter elements can be releasably secured at the fluid flow passages in such a way that the fluid flow passages are connected to the inner filter cavity, which is surrounded by the filter medium.

In this respect, the arrangement can be configured with a distinct advantage in such a way that the filter housing has a circularly cylindrical section, which receives the basket and exhibits an opening that can be closed by a removable cover. In this case, the basket can be inserted and removed through the opening, and the support plate is circularly round and circumferentially sealed off at the housing wall in the installation position.

If an abutment ring, which projects from the inner wall, is provided for supporting the support plate of the basket in the filter housing, then the procedure for replacing the filter can be carried out in a very simple and convenient way, because all one has to do to remove the basket is to lift the basket off of the abutment ring, and to re-install the basket, one need only place the basket down on the abutment ring, so that no additional installation steps are necessary.

In order to secure the basket in the functional position during a filtering operation, the interior of the cover can have at least one axially projecting hold-down device. In order to hold the support plate of the basket on the abutment ring, this hold-down device extends through a clean-side outflow space, in which a housing outlet for the cleaned fluid is located.

The arrangement can be configured with a distinct advantage in such a way that the element holders for securing the filter elements in the form of filter cartridges comprise a connecting device, which secures a fluid permeable support cylinder at the respective fluid flow passage of the support plate in such a way that an assigned filter cartridge can be pushed onto the exterior of the support cylinder and pulled off from the same. Owing to such a support cylinder, even filter cartridges exhibiting a longer length and correspondingly large filter surface area can be held securely in position, so that at the same time the replacement steps can be performed easily and conveniently by stripping them off the associated support cylinder.

Additional advantageous features of the filter device are disclosed in the dependent claims 7 to 9.

According to claim 10, the subject matter of the invention is also a filter cartridge for use in a filter device according to one of claims 1 to 9, with the filter cartridge having preferably at least two filter elements, which are designed as identical parts and have a filter medium, which surrounds an inner filter cavity; and the respective end of said filter medium is enclosed by an end cap, which leaves open the access to the inner filter cavity. The respective filter elements are arranged coaxially to each other and are sealingly connected to each other at the end caps that interact with each other. If in this case there are, for example, three filter elements and each one of these filter elements exhibits a filter surface area of about 5 m², so that each filter cartridge has a filter surface area of about 15 m², then it is possible to provide a requisite total filter surface area of more than 500 m² with 36 filter cartridges. When arranged in a removable basket, even such a large number of filter cartridges can be housed in a single filter housing in such a way that they are easy to service.

Furthermore, the subject matter of the invention is also a filter element, which is a component of a filter cartridge according to claim 10 and is characterized in that in order to form sealed connections between a plurality of filter elements, which are formed by means of identical parts and are arranged coaxially to each other, the filter element has an end cap of a first type and a complementary end cap of a second type. In such a design of the end caps, the individual elements can be easily stacked in order to form a filter cartridge composed of a plurality of elements.

Preferably, the arrangement is configured in such a way that at least the end cap of one type has a sealing element for forming a seal with the end cap of the respective other type of the adjacent additional filter element, so that the seal is formed when the end caps lie next to each other.

At the same time, the end cap of the first type has in an especially advantageous way a funnel at its opening, which forms the access to the filter cavity, with this funnel expanding conically outward the opening of said end cap. The end cap of the second type has an axially projecting annular body which surrounds the opening, with this annular body forming an outer cone for a fitting engagement with the funnel of the end cap of the first type.

In order to form a seal between the adjacent elements, an O-ring can be arranged on the inside of the funnel of the end cap of the first type in order to form an axial and radial seal that is easy to disassemble.

The invention is explained in detail below by means of one exemplary embodiment that is depicted in the drawings. Referring to the drawings:

FIG. 1 shows one exemplary embodiment of the inventive filter device in a perspective oblique view and cut in the longitudinal direction;

FIG. 2 is a perspective oblique view of the basket of the exemplary embodiment from FIG. 1; however, this basket, which is provided as the carrier for filter cartridges, is drawn to a larger scale than in FIG. 1;

FIG. 3 shows a single representation of a filter cartridge of the exemplary embodiment shown in a perspective oblique view;

FIG. 4 is a longitudinal view of the filter cartridge from FIG. 3;

FIG. 5 is a longitudinal view of the filter cartridge from FIG. 4, and this view is shown with breaks and is drawn to a larger scale than in FIGS. 3 and 4;

FIG. 6 is a longitudinal view, drawn to an even larger scale, of a single filter element of the filter cartridge from FIGS. 3 to 5; and

FIG. 7 shows an enlarged detail of the region designated as VII in FIG. 6.

The invention is explained below with reference to the drawings by means of a line filter as an example which can be used with a distinct advantage for fine filtering of sea water, which can be conveyed from a drilling platform of an offshore oil field into this oil field in order to increase the pressure where high volumetric flow rates are to be filtered at a filter fineness of 5μ with filter surface areas in the range of 500 m². FIG. 1 shows a filter housing 1 with a fluid inlet 3 for the inflow of sea water to an unfiltered space 5 of the housing 1. The outflow space 7 on the clean side has an outlet 9 on the housing 1. The housing 1 has a circular cylindrical shape, aside from a curved, closed bottom part 11, and has an upper opening 13, which can be closed with a removable cover 15. The cover 15 can be rotated and removably secured at the housing 1 by means of a bayonet lock 17.

Between the inflow space 5 on the unfiltered side and the outflow space 7 on the clean side, there is the filter arrangement consisting of a basket 19 as a carrier for a number of filter cartridges 21, which are not all numbered in the drawing. The basket 19, which is shown in a single representation in FIG. 2, can be inserted through the opening 13 into the housing 1 and removed from said housing. As the carrier element for the filter cartridges 21, the basket 19 has a circularly round support plate 23, which rests against-an abutment ring 25, which projects at the interior of the housing 1, when the basket 19 in its functional position is inserted into the housing 1, so that a collar 27 of the support plate 23 is sealed off at the abutment ring 25. The support plate 23 separates the inflow space 5 on the unfiltered side from the outflow space 7 on the clean side in the housing 1. In order to hold the basket 19 in engagement with the abutment ring 25, the cover 15 has a plurality of rod shaped hold-down devices 29, which extend from the cover 15 axially through the outflow space 7 to the support plate 23.

The latter has a fluid flow passage 31 for each filter cartridge 21, of these fluid flow passages only some of them being numbered in FIG. 1 for the sake of a better overview. In the example shown in the drawing, 36 fluid flow passages 31 are provided to match the 36 filter cartridges 21. At each fluid flow passage 31, there is an element holder, at which the respective filter cartridge 21 can be releasably secured. This feature is shown in greater detail in FIGS. 3 to 7.

The filter cartridges 21, shown in the single representation in FIGS. 3 to 5, are constructed in each instance from three stacked filter elements 33, formed by identical parts, with one of these filter elements being shown in the single representation in FIG. 6. These filter elements have a filter medium 35, which conventionally surrounds an inner filter cavity 37 in the form of a hollow cylinder, for example, in conformity with the line filter PLF1, marketed by the applicant; and this filter medium provides a large pleated filter surface area. Such filter media can contain a polyester material and/or polypropylene and can be multi-layered. In the present case, the filter medium 35 is surrounded by a support fabric 39 (see FIG. 7). Similarly, in this case a mesh pack can be provided. On the end side, the filter medium 35 is enclosed by a respective end cap 41 and 43, which are made of polyamide in the present example. The resulting filter element 33 can be totally ashed as a disposable element. Such a filter element can provide a filter surface area of about 5 m², so that a filter cartridge 21 with three filter elements 33 provides about 15 m² of filter surface area. If, for an application for increasing the pressure of sea water, a total filter surface area of about 500 m² is necessary, then this requirement can be met by providing 36 slots for the filter cartridges 21 in the basket 19 of the filter housing 1, as shown in the illustrated example.

For easy stacking of the filter elements 33, the end caps are designed differently at one and the other end in such a way that one end cap 41 of the first type has a shape that is complementary to an end cap 43 of the second type. More specifically, the end cap 41 of the first type has an axially projecting funnel 47, which is expanded conically outward and surrounds the cap opening 45. An O-ring 49 may be found on the inside of said funnel. The end cap 43 of the second type has an axially projecting annular body 51, which is connected to the opening 45. This annular body forms an outer cone for a fitting engagement with the funnel 47 of the end cap 41 of the first type. Therefore, when the individual elements 33 are easily assembled in order to form the filter cartridge 21, an axial/radial seal is formed in each instance between the end caps 41, 43.

The filter cartridges 21 can be releasably secured at the fluid flow passages 31 of the support plate 23 of the basket 19 by means of a connecting device, which has a star-shaped retaining body 53 which extends over the top side of the support plate 23 (see FIG. 4) and at which a connecting rod 55 is secured with its one end. The connecting rod 55 extends in the axial direction as far as beyond the lower end of a filter cartridge 21 that is to be secured; see, in particular, FIG. 4. In the region of the corresponding end, the connecting rod 55 is provided with an outer thread 57. It is very clear from FIG. 5 that the connecting rod 55 is used to secure a fluid permeable support cylinder 59, which forms a displaceable mounting for a filter cartridge 21 that is pushed on, at the support plate 23 of the basket 19. For this purpose, a holding disk 61 is screwed with a nut 66 on the thread 57 of the connecting rod 55 in such a way that the holding disk 61 clamps the support cylinder 59 against a conical ring 63 and by way of the latter against the support plate 23. The conical ring 63 is sealed off at the support plate 23 by means of an O-ring 65 and engages with the funnel 47 of the adjacent end cap 41. The tightening nut 67 for the holding disk 61 is secured against loosening at the holding disk by means of a sheet metal lock 67.

In order to hold the respective filter cartridges 21 in position on the support cylinder 59 in such a way that the elements 33 are sealed off from each other at the end caps 41, 43 and that the end cap 41 of the uppermost element 33 is in sealed fluid connection with the fluid flow passage 31 of the support plate 23 by means of the conical ring 63, the free end of the connecting rod 55 has a wing nut 69 on the thread 57. With this wing nut, a locking body 71 can be releasably pressed against the end cap 43 of the bottommost element 33, as a result of which the end cap 41 of the uppermost element 33 is held against the conical ring 63 and is sealed off thereat by means of the O-ring 49. The locking body 71 in turn is sealed off at the assigned end cap 43 by means of an O-ring 73. As a result, the clean-side filter cavity 37, which is connected to the outflow space 7 by means of the fluid flow passage 31, is connected to the inflow space 5 on the unfiltered side only by way of the filter medium of the filter cartridges 21, but is otherwise sealed off.

When for the purpose of a replacement operation the basket 19 with the used filter cartridges 21 is lifted out of the housing 1, for example, by attaching a lifting means at the lifting eye 75, and is set down in a position in which the bottom side of the basket 19 is freely accessible, as shown in FIG. 2, then the holding disk 71 can be removed by loosening the wing nuts 69, with only some of the wing nuts being numbered in the drawing, so that the filter cartridges 21 are released and can be pulled off from the support cylinder 59. After the new filter cartridges 21 are pushed on and fastened with tightening screws of the holding disks 71, the re-equipped basket 19 is ready again for insertion into the housing 1. FIGS. 1 and 2 show that the basket 19 has an enclosing ring 77, which surrounds, concentrically to the collar 27 of the support plate 23, the group of filter cartridges 21 at their bottom, free end and is connected to the collar 27 by way of struts 79, which are welded to the collar 27 and the ring 77 and on which lifting eyes 75 for handling the basket 19 are likewise attached. 

1. A filter device for fluids, in particular for low viscosity fluids such as water, comprising a filter housing (1) in which element holders (31) are provided for a plurality of filter elements (21), whose filter medium (35) in the filter housing (1) separates an unfiltered side (5) from a clean side (7), wherein the filter housing (1) can be opened for the purpose of inserting and removing the filter elements (21), characterized in that a carrier in the form of a basket (19) is provided for the filter elements (21), said basket can be inserted into and removed from the filter housing (1), and the filter elements (21) can be releasably secured at said basket.
 2. The filter device according to claim 1, characterized in that the basket (19) has a support plate (23), which in the installation position in the housing (1) separates the unfiltered side (5) from the clean side (7) and has fluid flow passages (31) for forming the element holders; and the filter elements (21) can be releasably secured at the fluid flow passages in such a way that the fluid flow passages (31) are connected to the inner filter cavity (37), which is surrounded by the filter medium (35).
 3. The filter device according to claim 1, characterized in that the filter housing (1) has a circularly cylindrical section, which receives the basket (19) and exhibits an opening (13) that can be closed by means of a removable cover (15), and the basket (19) can be inserted and removed through the opening, and that the support plate (23) is circularly round and in the installation position is circumferentially sealed off at the housing wall.
 4. The filter device according to claim 1, characterized in that an abutment ring (25), which projects from the inner wall, is provided for the support of the support plate (23) of the basket (19) in the filter housing (1).
 5. The filter device according to claim 1, characterized in that the interior of the cover (15) has at least one axially projecting hold-down device (29), which in order to hold the support plate (23) of the basket (19) at the abutment ring (25), extends through a clean-side outflow space (7), in which a housing outlet (9) is located.
 6. The filter device according to claim 1, characterized in that the element holders for securing the filter elements in the form of filter cartridges (21) comprise a connecting device (53, 55, 59, 61), which secures a fluid permeable support cylinder (59) at the respective fluid flow passage (31) of the support plate (23) in such a way that an assigned filter cartridge (21) can be pushed onto the exterior of the support cylinder (59) and pulled off from the same.
 7. The filter device according to claim 1, characterized in that the connecting device (53, 55, 59, 61) has at each fluid flow passage (31) a connecting rod (55), which is anchored to said fluid flow passage and which extends through the support cylinder (59) and has in the region of its free end a threaded joint (57, 66) for securing a holding disk (61), which extends over the end edge of the support cylinder (59) and presses it against the support plate (23).
 8. The filter device according to claim 1, characterized in that the filter cartridge (21), which is pushed onto the respective support cylinder (59), can be releasably secured by means of a locking body (71), which closes the filter cavity (37) at the end facing away from the support plate (23), in a functional position, in which the open end of the respective filter cartridge (21) is in sealed fluid connection with the associated fluid flow passage (31) of the support plate (23).
 9. The filter device according to claim 1, characterized in that the locking body (71) can be releasably secured by means of a releasable threaded joint (69) with the connecting rod (55) in a position that holds the filter cartridge (21) in a functional position.
 10. A filter cartridge for use in a filter device according to claim 1, having at least one, preferably at least two filter elements (33), which are designed as identical parts and have a filter medium (35), which surrounds an inner filter cavity (37), with the end of said filter medium being enclosed by an end cap (41, 43), which leaves open the access to the inner filter cavity (37), wherein the respective filter elements (33) are arranged coaxially to each other and are connected to each other in a sealed off manner at the end caps (41, 43) that interact with each other.
 11. A filter element as a component of a filter cartridge according to claim 10, with a filter medium (35), which surrounds an inner filter cavity (37) and which has an end that is enclosed in each instance by an end cap (41, 43), which leaves open an access to the filter cavity (37), characterized in that in order to form sealed connections between a plurality of filter elements (33), which are formed by means of identical parts and are arranged coaxially to each other, the filter element has an end cap (41) of a first type and a complementary end cap (43) of a second type.
 12. The filter element according to claim 11, characterized in that at least the end cap (41) of one type has a sealing element (49) for forming a seal with the end cap (43) of the respective other type of the respective adjacent additional filter element (33).
 13. The filter element according to claim 11, characterized in that the end cap (41) of the first type has a funnel (47) at its opening, which forms the access to the filter cavity (37), with this funnel expanding conically outward the opening of said end cap, and that the end cap (43) of the second type has an axially projecting annular body (51), which surrounds the opening and forms an outer cone for a fitting engagement with the funnel (47) of the end cap (41) of the first type.
 14. The filter element according to claim 11, characterized in that an O-ring (49) is arranged on the inside of the funnel (47) of the end cap (41) of the first type. 